This invention relates generally to the field of reflector antennas and horizontally polarized wave antennas.
As is widely known, in the art of antennas which have hitherto been in use, there have been difficult problems concerning the special arrangement of antenna elements and the phase for excitation to obtain a specific, desired radiation pattern. Furthermore, they have a shortcoming in that their dimensions have to be large because of the necessity to increase the generated voltage.
It is useful for the purposes of mathematical analysis of antennas to describe the radiation from a small loop of current by replacing it with an equivalent magnetic dipole which carries a fictitious magnetic current. This so called magnetic current is a fictitious quantity represented by a vector whose magnitude M is proportional to the current I flowing in a small conductive loop and whose direction is perpendicular to the plane of said loop. With this in mind, the antenna of the present invention will be described in terms of such a magnetic current for the sake of convenience and clarity.
Hitherto, it has also been considered impractical to obtain pure magnetic current radiation (radiation from a small loop current) in appreciable quantities to provide a practical antenna which has a pure magnetic current distribution. The single minor electric loop of current previously described is so small and insignificant that it alone does not provide a practical or realizable magnetic current antenna for any known present day application. Also the single larger loop antenna of today does not solve this problem as it loses the characteristics of the minor electric loop and can no longer be equated to a pure magnetic current distribution having horizontally polarized waves alone. So also a helical coil of small diameter alone does not overcome this problem as such helical antennas are either elliptically or circularly polarized. Until the present invention, no one has effectively eliminated the vertical polarized wave component from a helix radiating an elliptical polarized wave to produce horizontal polarized wave radiation alone thereby providing an antenna with an effectively pure magnetic current radiation. Thus the prior art has been unable to supply an antenna which comprises many small or minor electric loop currents to provide an effective and practical magnetic current antenna. It is only the minor electric loop which provides pure so-called magnetic current but hitherto no one has conceived a practical means of employing it to provide a magnetic current antenna.